However, Mredxwx took to YouTube himself to deny responsibility, saying: "I did not hack Sesame Street. I am an honest youtuber. I work hard to make quality gameplayer videos AND MOST IMPORTANT I RESPECT THE COMMUNITY GUIDELINES'.

Security expert Graham Cluley of Sophos says it's unclear exactly how the channel got hacked, but that it was probably through sloppiness over passwords.

"What would Bert and Ernie say?" he says.

" The truth of the matter is that the channel is regularly visited by young children, and parents trust that the page will be safe for them to view."